Solid State Physics Laboratory

About: Solid State Physics Laboratory is a facility organization based out in Delhi, India. It is known for research contribution in the topics: Quantum dot & Dielectric. The organization has 1754 authors who have published 2597 publications receiving 50601 citations.

A comparative analysis of one-port Colpitt and two-port Pierce SAW oscillators for DMMP vapor sensing

Abstract: This paper reports an experimental study on chemical sensitivity and noise behavior of Colpitt and Pierce SAW oscillators based on 433.92 MHz one-port and two-port SAW resonator devices, respectively. The oscillators are characterized for phase noise as well as Allan variance. The sensitivity for DMMP (di-methyl methyl phosphonate) vapor is imparted by providing a diallyl-bisphenol polymer precursor as a selective interface coated on to both the SAW devices in an identical manner. Comparative vapor sensing experiments are carried out under simultaneous exposure to the same DMMP vapor stream in different ranges of vapor concentration and duration. A new data acquisition method is employed which is wireless and automated. It uses an antenna pickup at the input of a spectrum analyzer with PC control interface. The results show that the two-port Pierce oscillator is more stable but less sensitive than the one-port Colpitt oscillator. It is found that under the conditions of analyte exposure durations longer than 30 s the one-port Colpitt oscillator yields higher signal to noise ratios. The results are interpreted in terms of phase response characteristics and different sensitivities of the one-port and two-port SAW devices towards mass loading and viscoelastic effects.

Electrical and magnetic studies of the spinel system Li0.5+tCrxSbtFe2.5-x-2tO4

Abstract: The lattice constant, dc resistivity, dielectric constant, saturation magnetization and Curie temperature were studied on a series of Cr-substituted Li-Sb ferrite systems. The dc resistivity increases with increase of the chromium level. A change in slope was observed in the variation of resistivity with temperature and hence two regions of different activation energy. The study of dielectric permittivity with frequency showed dispersion for the whole system. The saturation magnetization and the Curie temperature were found to decrease with increase of the substitution level.

New insights into the structure of b2o3 glass

Abstract: The results of structural investigations of various types of B 2 O 3 glass with different thermal histories are presented. The density and the glass transition temperature T g depend on the cooling rate at which the glass is quenched. For quickly quenched glass (cooling rate 10 3 K/s) the density is 1.79 g/cm 3 and T g is 278°C whereas these values for slowly quenched glass (cooling rate 4 × 10 −3 K/s) are respectively 1.83 g/cm 3 and 298° C. X-ray diffraction and Molecular Dynamics simulations show that the structure of vitreous B 2 O 3 can be explained by a model of randomly connected BO 3 triangles. The slower the glass is quenched, the more the BOB angles of adjacent BO 3 units approach 120°. We have found no tendency of neighbouring BO 3 triangles to form equiplanar complexes if the cooling rate decreases and therefore we have found no evidence for the existence of boroxol rings. The combination of the results of density measurements and X-ray diffraction studies indicates that for the slowly quenched glass the oxygen tend to be out of the plane of adjacent BO 3 triangles. This results in a more densely packed glass structure for slowly quenched B 2 O 3 glass.